In certain distributed computing systems, a work manager computing system receives work assignments from client devices and assigns and distributes the work via one or more intermediaries to recipients that perform the work. The work assignments are typically sent over a network, which may be a private network or an open or public network, such as but not limited to the Internet. The results of the work assignment may be sent, if appropriate, from the recipient to the work manager computing system over the network, again via one or more intermediaries.
A problem may occur if a work assignment is somehow altered before it reaches the recipient and/or the work results (the results of executing the work assignment) are altered after they are returned by the recipient. A work assignment may be altered accidentally due a hardware error, a software error, or another type of error, or may be intentionally altered, such as when an intermediary has become corrupted by malware, such as but not limited to a virus, or when an intermediary has obtained credentials that allow it to pose as an intermediary or as a recipient. Intentional tampering of this sort is often referred to as a “man-in-the-middle” (“MITM”) attack.
A problem might also occur if an intermediary acknowledges the work assignment but does not forward the work assignment to the recipient, or does not return, if appropriate, the work result from the recipient. This may happen accidentally due to a hardware error, a software error, or another type of error, or may be intentional, such as the result of a “denial-of-service” (“DoS”) attack. MITM, DoS, and other types of attacks are often hard to detect, especially if the expected result expected does not need to contain proof of work, or if the work expected will take a substantial amount of time to perform. It is also often difficult to identify the intermediary or recipient that is the location of the problem.
It is with respect to these and other considerations that the disclosure presented herein has been made.